Fix //content/test:test_support under component builds.

content/gpu/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/ui.gni")
 import("//content/content.gni")
 
-source_set("gpu") {
+# See //content/BUILD.gn for how this works.
+group("gpu") {
+  visibility = [ "//content/*" ]
+
+  if (is_component_build) {
+    public_deps = [
+      "//content",
+    ]
+  } else {
+    public_deps = [
+      ":gpu_sources",
+    ]
+  }
+}
+
+source_set("gpu_sources") {
   visibility = [ "//content/*" ]
 
   sources = [
     "gpu_child_thread.cc",
     "gpu_child_thread.h",
     "gpu_main.cc",
     "gpu_process.cc",
     "gpu_process.h",
     "gpu_watchdog_thread.cc",
     "gpu_watchdog_thread.h",
@@ skipping 25 matching lines @@
   }
 
   if (is_chromeos && current_cpu != "arm") {
     configs += [ "//third_party/libva:libva_config" ]
   }
 
   if (use_x11) {
     deps += [ "//ui/events/platform/x11" ]
   }
 }